Method of and device for pressing grinding wheel blanks



A ril is, 1958 K GEPPERT 2,830,320

METHOD OF AND DEVICE FOR PRESSING' GRINDING WHEEL BLANKS Filed April 12 1954 United States Patent METHOD OF AND DEVICE FOR PRESSING GRINDING WHEEL BLANKS Karl Geppert, Schweinfurt, Germany, assignor to Kugelfischer Georg Schafer & Co., Schweinfurt, Germany Application April 12, 1954, Serial No. 422,614

Claims priority, application Germany April 20, 1953 2 Claims. (Cl. 18-9) In the manufacture of grinding wheels and the like methods have heretofore been used whereby a suitable material is used either in a crumbly condition, such material being molded in a suitable die by the application of static pressure, or in a fluid condition in which case the material is cast into a suitable mold. In the latter case, however, it has been known that the prolonged drying period required by this known method will cause the compacting of the material to proceed relatively slowly. Moreover, it is necessary with the first mentioned method to apply a very high pressure, and both of the abovementioned methods have been known not to result in grinding wheels having the desired uniform structure.

To eliminate the drawbacks indicated above, the invention provides for a method whereby the material is compacted and shaped by it being urged against rotating tapered rollers. In a specific embodiment of the invention the thus shaped blank, after removing the roller support carrying said tapered rollers, is ejected from the form or mold by means of ejector plungers provided on the bottom of the mold, the blank then being lifted oif. The process according to the invention is carried out in a mold or die comprising an external annular wall member, a centrally disposed boss coaxial with said wall member, and a movable bottom plate, the said mold or die being supported in any suitable manner directly below a rotatable roller carrier comprising two rotatably supported rollers arranged to roll on the said annular wall member and said cental boss.

Futher objects and features of the invention will be apparent from the following description taken in conjunction with the appended drawings illustrating a preferred embodiment of the invention and in which:

Figure 1 is a part-sectional front elevation of the device according to the invention, filled with material, in its initial position;

Figure 2 is a similar illustration to Figure 1 and shows the bottom plate of the device in its extreme raised position; and

Figure 3 illustrates the operation of ejecting the finishrolled grinding wheel blank from the device.

Grinding wheel blanks of the type indicated are made according to the invention in a molding die comprising 'an external annular wall member a, a boss b and a movable bottom plate 0. With the bottom plate in its lowermost position, a predetermined amount of material g is poured into the molding die. Thereupon the rotatable roller carrier together with its two rotatably mounted tapered rolelrs e, is lowered into a position in which, upon the roller carrier f being rotated, the two rollers e will be rotated about their respective journals h and will roll on the annular member a and the boss b. The roller carrier 2,830,320 Patented Apr. 15, 1958 f may be driven for rotation by any conventional means which form no part of the invention and which are, therefore, not shown in the drawings. While the roller carrier is being rotated, the bottom plate c is moved by the plungers d towards the rotating tapered rollers e an amount sufiicient to produce a grinding wheel blank of the desired thickness and density, the plungers d being actuated by suitable hydraulic or mechanical means (see Fig. 2).

During the compression of the material g within the forming die the rotating rollers will subject the material to a final kneading action. It has been found that gn'nding wheel blanks made by this process show a highly uniform structure throughout. Moreover, this process requires considerably less pressure than prior-art pressing methods.

Upon the pressed blank 3 (Figure 3) having been given the desired thickness and density, the roller carrier 7, together with the rollers e, is lifted off the forming die. Following this, the blank g is ejected from the die a, b by the bottom plate c actuated by the plungers d', whereupon the blank is simply lifted off the bottom plate.

It will be appreciated that the method according to the invention may also be conveniently used in the manufacture of pressed bodies consisting of turning or other scrap metal as well as in the shaping of bodies made of other types of material.

I claim:

1. The method of manufacturing grinding wheel blanks which includes pouring a mass of unconsolidated grinding wheel composition into a mold cavity provided with a movable bottom plate, positioning a pair of conical rollers to engage and roll upon the periphery of said mold cavity, compacting said composition by simultaneously rotating said rollers and elevating said bottom plate to reduce the volume defined by said mold cavity, and ejecting said compacted grinding wheel composition.

2. In an apparatus for producing grinding wheel blanks from molding material with a supply of abrasive contained therewithin, a central boss, a cylindrical annular member concentrically disposed with respect to said boss to form a molding cavity in the space therebetween, a bottom plate slidably mounted on said central boss for axial movement within said annular chamber, plunger means adapted to abut said bottom plate when actuated to reduce the volume occupied by said molding material within said molding cavity during the molding operation and eject said completed blank at the termination thereof, a roller carrier provided with journals and positioned above said central boss and said cylindrical annular member and movably mounted for vertical elevation therefrom, and a plurality of substantially conical shaped rollers mounted each in rolling contact one with the other for rotation on said journals, each of said conical shaped rollers disposed in such a manner that it will contact said central boss at its apex and said annular member at its base and roll in a plane contiguous to the upper surface of said boss and said cylindrical annular member.

References Cited in the file of this patent UNITED STATES PATENTS 945,931 Gardner Ian. 11, 1910 1,307,788 Nall June 24, 1919 1,337,254 Muench Apr. 20, 1920 1,423,009 Muckenhirn July 18, 1922 

